Chapter 11 IPsec VPN for FortiOS 5.0 : L2TP and IPsec (Microsoft VPN) : Troubleshooting : Setting up logging
  
Setting up logging
L2TP logging must be enabled to record L2TP events. Alert email can be configured to report L2TP errors.
To configure FortiGate logging for L2TP over IPsec
1. Go to Log & Report > Log Config > Log Settings.
2. Select Event Log.
3. Select the VPN activity event check box.
4. Select Apply.
To view FortiGate logs
1. Go to Log & Report > Event Log > VPN.
2. Select the Log location if required.
3. After each attempt to start the L2TP over IPsec VPN, select Refresh to view logged events.